Fire-alarm transmitter.



W. R. HAMILTON.

FIRE ALARM TRANSMITTER.

APPLIUATION FILED APImz. 191s.

1,128,199, Patented Jan.26,1915.

UNITED STATES PATENT OFFIC VILLIAM R. HAMILTON, 0F MONTREAL, QUEBEC,CANADA, ASSIGNOR TO THE DOMINION GRESHAM GUARANTEE & CASUALTY COMPANY,OF MONTREAL, CANADA, A CORPO- RATION OF CANADA.

FIRE-ALARM TRANSMITTER.

Specification of Letters Patent.

Patented Jan. 26, 1915.

T0 all whom it may concern Be it known that I, IVILLIAM R, HAMIL- rroN,of the city of Montreal, in the Province of'Quebec and Dominion ofCanada, have invented certain new and useful Improvements in Fire-AlarmTransmitters, of which the following is a full, clear, and exact de--scriptioir reasons been almost universally operated on closed circuitprinciple, and require two transmitters, one of which transmits thealarm signal, while the other maintains the system under constant testso as to .send a different signal if any part of the instrument orsystem except the signal circuit gets out of order. The disadvantage ofthis arrangement is that a defect in the signal circuits may beequivalent to the operation of the alarm transmitter, so that whatshould be a trouble signal on these circuits is transmitted as an alarmsignal, thus sending to the central station a false alarm. Thesedisadvantages are overcome in the present invention by using only asingle transmitter for both the alarm and trouble signals, and soarranged as to be controlled by a single circuit. Any disarrangement ofthis circuit other than that prearranged for the sending of an alarmsignal will transmit a trouble signal only.

In the drawings which illustrate the inventionr-Figure 1 is a frontelevation of the transmitter. Fig. 2 is a circuit diagram showing theoperating elements connected to the transmitter.

Referring more particularly to the drawings, 5 designates the frame of aspring driven clock movement controlled by a lever 6 carrying a catch 7movable into and out of the path of the fan 8 to release or stop theclockwork movement. An electro-magnet 9 is provided having lowresistance windings 9L and 9b of equal resistance. -These two windingsare so arranged that the current liow is in opposite directions, so

that while the current iows through both windings, the magnetism inducedby one winding is neutralized by the magnetism induced by the otherwinding, so that the magnet is denergized and does not draw up itsarmature l0. This armature is mounted on the lever 6 and is providedwith a lever arm 11 projecting into the path of a cam (not shown)mounted behind the signal wheels 12. A small spring 13 is provided tonormally hold the armature 10 away from the magnet 9, so that the stop 7remains in the path of the fan 8.

At a suitable point on the movement, an electro-magnet 111 of higherresistance than the magnet 9 is provided, having an armature 15 carriedon one arm of a bell-crank lever 16. The other arm of this bell-cranklover is provided with a pin 17 which is normally in engagement with orin very close proximity to the lever 11. The arm of the lever 16carrying the armature is provided with a pin 18 positioned to be engagedby a cam 19 carried on the same spindle as the commutator 20. This cam19 has a recessed portion 21 which is positioned under the pin 18, whilethe transmitter is at rest, as is clearly shown in Fig. 1.

One transmitter, such as above described, is mounted in each protectedbuilding and is connected in series with abattery or other source ofenergy 22 and with a detecting device, indicated at 23. This detectingdevice may be of any desired type, such as a galvanometer, relay or likeinstrument, having a circuit maker 24 adapted to engage a contact 25when operated and to engage a contact 26 when out of order. The currentlow from the battery is through wire 27 to winding 9LL of magnet 9, andthrough the wire 28 to the contact 25. From the contact 25, the 'low isthrough wire 29 to winding 9b. After passing through the winding 9b, thecurrent flows through wire 30 to the contact 26 and from the contactthrough wire 31 to the magnet 14C. After passing through the magnet 14,the current returns to the battery through wire 32 in which is insertedthe circuit maker 24.

It will be seen from the foregoing that all the elements including thecontacts are in series. Tap wires are not used to connect the contactsand circuit maker into the circuit for the reason that the breaking ofthese taps would not destroy the circuit, so that no indication ofdisorder would be given. It will be remembered that the magnet 9 isofvlowresistance and 'the magnet 14 of high resistance,and also that thewindings 9a and 9b of the magnet neutralize, so that during current flowthrough both windings the core is demagnetized. 1t is therefore obviousthatf'if either' lof the windings of the magnet 9 is short circuited,there will be nothing to neutralize the ell'ect of the other winding, so`that the magnet becomes energized and tends to draw up its armature.However, as long as the high resistance magnet 14 remains in i' thecircuit, 'there would not be suiiicient current flow through theremaining winding of the magnet 9 Ato energize the same. Therefore, themagnet 14 is arranged as shown in the diagram, F ig. v2, so that whenthe winding 9b is short circuited the magnet 14 will also be shortcircuited, and allow the full strength of current flow through thewinding 9a. It will be seen at a glance from Fig. 2 that the con-v tact26 is so vpositioned in the circuit that when engaged bythe circuitmaker 24, the magnet 14will be short circuited and that when the contact25 is engaged by the circuit maker, the magnet 14 and one winding ofthe'. magnet 9 will be short circuited.

1,. With thefforegoing points in mind, the operation will be easilyunderstood and is as follows The detecting instrument 28 when 1in itsnormal condition holds ythe. circuit maker 24 midway between thecontacts 25y and 26. Any failure of the instrument removes or reducesthe holding effect on the circuit maker, vso that it is thrown againstthe Contact 26 and short circuits the magnet 14- of the transmitter.This magnet releases its armature 15 which drops by gravity and by meansof the pin 17 throws the lever l11. This lever is connected through thearmaturelO- with the control lever 6 of the transmitter movement, andtherefore operates the control -lever towithdraw the stop 7 from thefan, and thus release the' movement which operates the signal wheels 12to transmit a signal to the central station. Vhen the transmitter hasrepeated its signal a predetermined number of times, for example, twice,the cam 19 engages the pin 18 and raises the lever 16, thus releasingthe lever 11 and permitting the 4spring 13 to shift the control lever 6and stopA the transmitter movement. The cam now holds :the armature 15.up until the trouble is repaired and the transmitter rewound to bringthe notch 21 under the pin 18. If the instrument 23 is operated by thefire or burglar protection circuits, `it throws the circuit. maker 24against contact 25 so that the winding 9b of magnet `9 and the magnet 14are' both' shorttcircuited. The magnet 9v now energized by itswinding 9adraws up the armature 10 and releases the transmitter movement, aspreviously described. The neutrali zation of the magnet 9 by the shortcircuiting of its winding 9b and the increasing current flow permittedby the short circuiting of the magnet 14, enables the magnet 9 op- 70erated by its winding 9L to hold up its armature 10 as long as thebattery remains active. The transmitter thus continues operating untilrun .down and sends in its signal a greater number of times than whenoperater by the magnet 14,\for example, ve times. During this condition,the mechanical restoration of the armature 15 and lever 16 previouslyexplained will have no eifect whatever' on the transmitter, as themagnet 33 9 continues to hold olf the stop of the movement until thetransmitter is rewound and set. The magnet 14 being of higher resist-vance than vthe magnet 9 requires a stronger current to operate it, andwill therefore naturally become inoperative owing to battery failure,while there is still ample current to operate magnet 9. Thus, it mighthappen that with avweakened current, the magnet 14 would be able to holdup its armature, 90 but would not be able to lift the armature torestore the transmitter to normal. Any current strong enough to operatethe magnet 14 to hold up its armature would obviously be strong ,enoughto enable the magnet 9 95 to hold up its armature. Thus, if thetransmitter was operated by the fire detecting device, the magnet 14would be short circuited and drop its armature, which would operate aspreviously described to throw the armature 10 against the magnet. -Themagnet 9` would then hold it upfwithout difficulty. ThenI a batterybecomes very muchweakened, the high resistance magnet 14naturally failsrst and drops its armature irre- 195 spective of the action of anydetecting device. If now the detecting device operated the transmitterbefore the transmitter was re-set and the batteries replaced, therewould still be suiiicient current to operate themagnet 9 when the magnet14 was short circuited, and the transmitter would send in the number ofsignals remaining between the trouble signal and the alarm signal, whichfor the instances previously cited would be three times. If any wire isbroken, the `circuit is broken and the instrument 23 throws its circuitmaker 24 against the contactl 26, thus short circuiting the magnet 14.

In most instances, the device would op- 1.20 erate without thenutralizing winding 9b as the high resistance magnet 14 would pre-` ventan operative current flow through the winding 9a. If, however, anunusually strong battery was installed or the wiring 126 within thekbuilding became charged from another system, the first time themagnet14 was denergized there would be sufficient current flow to operate themagnet 9, so that an alarm signal would be sent in place 130 of atrouble signal. The neutralizing winding obviates any possibleoccurrence of this accident, since no matter how great the current flowis the magnet 9 will remain inoperative until one of its windings isshort circuited.

The description and drawings must be regarded as purely illustrative andnot in any way limitative, since the application of the principle of theinvention to different forms of transmitter would obviously makenumerous changes in details of construction and arrangement.

I-Iaving thus described my invention, what I claim is l. In a signaltransmitter, the combination with a transmitter control device of a highresistance magnet and a low resistance magnet having two windingsarranged to neutralize one another, said magnets being arranged toindependently operate the control device, a detecting device, and analarm circuit connecting the high resistance magnet and both windings ofthe low resistance magnet and the detecting device in series. I

2. In a signal transmitter, the combination with a transmitter controldevice and a detecting device of a low resistance magnet arranged tooperate the control device and to be energized by the operation of thedetecting device, a circuit connecting the detecting device and lowresistance magnet, a high resistance magnet connected in series in saidcircuit and arranged to operate the control device independently of thelow resistance magnet, and means arranged to maintain the low resistancemagnet inoperative during increased current ilow caused by the shortcircuiting of the high resistance magnet.

3. In a signal transmitter, the combina- Copies of this patent may beobtained for creased current flow caused by short cir'- cuiting of thehigh resistance magnet.

5. In a signal system, a source of energy,

a detecting device and a transmitter, a high resistance and a lowresistance magnet arranged -to independently operate the transmitter,saidlow resistance magnet comprising two coils arranged to neutralizeeach other during current flow through both, a circuit closable by thedetecting device to short circuit the high resistance magnet, and asecond circuit closable by the detecting device to short circuit thehigh resistance magnet and one winding of the low resistance magnet,whereby current iiow through the remaining winding will energize the lowresistance magnet.

6. In a signal system, a source of electric energy, a detecting device,a mechanical self-stopping transmitter, a high resistance magnet and alow resistance magnet arranged to independently operate the transmitter,a circuit closable by the .detecting device to short circuit the highresistance magnet whereby the transmitter will be released, a` secondcircuit closable by the detecting device arranged to energize the lowresistance magnet, to release and hold the transmitter in releasedcondition independent of its/self-stopping feature, and a neutralizingcdil on said low resistance magnet arranged to hold the magnetinoperative during short circuited condition of the high resistancemagnet, only said neutralizing coil being short circuited simultaneouslywith the high resistance magnet by the detecting device to enableoperative current iiow through the low resistance-magnet.

In witness whereof I have hereunto set my hand, in the presence of twowitnesses.

WILLIAM R. HAMILTON.

Witnesses:

STUART R. W. ALLEN, G. M. MORELAND.

five cents each, by addressing the Commissioner of Patents,

Washington, ID. C.

